1. Field of the Invention
The present invention relates to a liquid discharge head that records by discharging recording liquid, and also, to a method for manufacturing a liquid discharge head. More particularly, the invention relates to a liquid discharge head to which recording liquid is supplied, and the inner surface of which is made lyophilic. The invention also relates to a surface modifying method of the inner face of the liquid discharge head, as well as to a method for manufacturing such liquid discharge head. In this respect, the liquid discharge head of the present invention is applicable not only to a general printing apparatus, but also, to apparatuses such as a copying machine, a facsimile equipment provided with communication systems, and a word processor provided with a printing unit, among some others. Further, the invention is applicable to a recording apparatus for industrial use, which is complexly combined with various kinds of processing apparatuses.
2. Related Background Art
The liquid discharge apparatus (ink jet recording apparatus) is a recording apparatus of the so-called non-impact type, which is characterized by its capability of recording on a recording medium of various kinds at high speed with almost no noise in recording. With such advantages, the liquid discharge apparatus is widely adopted as the one that bears recording mechanism for a printer, a copying machine, a facsimile equipment, or the like.
As the typical liquid discharge method of a liquid discharge head mounted on a liquid discharge apparatus of the kind, there is known the one that used electro-mechanical converting member, such as piezoelectric element, the one that irradiates laser or some other electromagnetic waves to generate heat for discharging liquid by the action of this heating, or the one that heats liquid by use of the electrothermal converting member, which is provided with heat generating resistive element, and discharges liquid droplets by the action of film boiling, among some others. For the liquid discharge head that uses the electrothermal converting member as the discharge energy generating element, the electrothermal converting member is arranged in liquid flow path. The electric pulse that serves as recording signal is supplied thereto for heating and providing thermal energy for ink. Then, by the utilization of bubbling pressure at the time of liquid bubbling (at the time of film boiling) generated by phasic changes of liquid at that time, fine liquid droplets are discharged from each of the fine discharge ports for the performance of recording on a recording medium. Generally, there are provided the discharge ports for discharging liquid droplets, and a supply system that supplies ink to the discharge ports.
A liquid discharge head of the kind is generally formed by bonding plural members. In other words, the head is structured, for example, by a heater board having a plurality of electrothermal converting members arranged thereon, the common liquid chamber, which is bonded on the heater board, for inducing recording liquid from outside to that bonding surface, and a ceiling plate having a plurality of liquid flow paths formed to communicate with the discharge ports through above each of the electrothermal converting members. Further, an orifice plate having a plurality of discharge ports, which are open thereon corresponding to the discharge ports, may be prepared as a separate member in some cases, and bonded together with the heater board and the ceiling plate so as to position the discharge ports at each end of the liquid flow paths, respectively.
For such ceiling place and orifice plate, it is preferable to use polysulfone, epoxy, or some other resin material, which facilitates the excellent formation of a highly precise structure. Also, for bonding between the heater board, the ceiling plate, the orifice plate, and others, silicon or epoxy sealant or bonding agent is usually used in order to prevent recording liquid from leaking out into the liquid discharge head when the recording liquid is supplied.
The material, such as polysulfone or epoxy, used for the ceiling plate and orifice plate as described above, has a comparatively low surface energy, and in the liquid discharge head, difference may occur in the surface energy between the heater board and the ceiling plate or the orifice plate. Also, the plural members that form the liquid discharge head as described above are usually bonded by use of sealant or bonding agent. Then, the sealant or bonding agent thus applied allows its water-repellent property to affect recording liquid in the area surrounding such bonding portions. As a result, even if the heater board has hydrophilic property itself, it tends to present hydrophobic tendency eventually on the area surrounding the portion where the heater board is bonded.
Then, particularly when the head is used for a long time, or in the similar condition, there is a fear that air accumulation is caused to take place near the ceiling plate or orifice plate where the surface energy is comparatively low, such as the bonded portion having sealant applied thereto in particular, as indicated at 105 in FIG. 16, for example: there occurs an air accumulation centering the portion surrounding the bonding portion between the heater board 101 and the ceiling plate 102 where sealant 103 is applied. If such air accumulation as indicated at 105 occurs, the discharge performance of recording liquid is caused to change or the colorant contained in recording liquid is caused to be condensed, because the recording liquid is in contact with air, among some other unfavorable influences that may be exerted.
Here, a method for suppressing the occurrence of such air accumulation is disclosed in the specification of Japanese Patent Laid-Open Application 11-42798, in which before ink is initially filled in a head, the liquid that has a high wettability is filled in the head so as to remove any hydrophobic film formed on the inner face of the head, and also, to cover the inner face with such liquid in order to fill ink in good condition. With this method, however, it is impossible to maintain such cover for a long time. After a certain period elapses, the sealant portion that has water-repellent property, or the like, is exposed on the inner face of the head, and then, there is a fear that air accumulation occurs eventually.
It is, therefore, an object of the present invention to solve the problems discussed above, and provide a highly reliable lipid discharge head capable of filling recording liquid inside in a good condition and maintaining such condition for a long time, and also, provide a surface modifying method for the inner face of the liquid discharge head, as well as a method for manufacturing such liquid discharge head.
In order to achieve this object, the liquid discharge head of the present invention, which records by discharge recording liquid, is characterized by having:
a first portion with lyophilic group for lyophilic processing on a partial surface formed at least on a part of the inner face having recording liquid internally filled to be in contact therewith, and a second portion with a group having substantially the same or the same interfacial energy as the surface energy of the partial surface but different from the interfacial energy of the lyophilic group, while the second portion being orientated toward the partial surface, and the first portion being orientated in the direction different from the partial surface.
With the structure thus arranged, the surface energy of the inner face of the liquid discharge head is essentially uniformalized, hence preventing air accumulation from being generated in the portion having lower surface energy.
The present invention is particularly effective for a liquid discharge head for which the portion where recording liquid is filled is formed by bonding a plurality of members together. In other words, bonding agent or sealant is used usually for bonding them, and for that matter, there occurs the portion that presents hydrorepellency on the inner face of the liquid discharge head. In accordance with the present invention, however, such portion is processed to be lyophilic to suppress the air accumulation thereon. Also, with the formation of the surface processed to be lyophilic, it becomes possible to suppress the generation of eluted substance from bonding agent or sealant. Particularly, in accordance with the present invention, it is possible to perform the lyophilic processing on the portion where bonding agent or sealant is exposed on the inner surface even when the bonding agent or the sealant is formed by silicon or epoxy material.
Also, when at least parts of plural materials themselves are formed by those having the surface different from each other, it becomes possible to make the surface energy of the inner face, which is formed by the materials having different surface energy from each other, essentially equal so as to suppress air accumulation on the portion having lower surface energy.
For the liquid discharge head formed by bonding a plurality of members as described above, there is a liquid discharge head comprising a base plate having discharge energy generating members for generating energy for discharging the recording liquid; a ceiling plate bonded to the base plate with grooves formed on the bonded face to constitute liquid flow paths communicated with discharge ports for discharging the recording liquid, being passed through above the discharge energy generating members; and an orifice plate having the discharge ports opened, and bonded to the base plate and the ceiling plate to enable the discharge ports to be communicated with the liquid flow paths. The liquid discharge head of the present invention is preferably applicable to a liquid discharge head of the kind.
Also, the present invention is preferably applicable to a liquid discharge head provided with a ceiling plate having integrally formed with the aforesaid orifice plate, that is, the liquid discharge head comprising discharge a base plate having discharge energy generating members for generating energy for discharging the recording liquid; and a ceiling plate bonded to the base plate with grooves formed on the bonded face to constitute liquid flow paths communicated with discharge ports for discharging the recording liquid, being passed through above the discharge energy generating members, the discharge ports communicated with the liquid flow paths being opened on the ceiling plate.
The aforesaid ceiling plate or orifice plate is formed by resin material containing polysulfone or epoxy. The resin material of the kind has comparatively low surface energy. The present invention is preferably applicable to the liquid discharge head having the ceiling plate or the orifice plate formed by a material of the kind. In other words, with the surface energy of the inner face formed by such ceiling plate or orifice plate being made essentially equal to that of the base plate, it becomes possible to suppress the air accumulation which is generated on the inner surface formed by the ceiling plate or orifice plate.
The surface modifying method of the present invention for the inner face of a liquid discharge head is the one for performing lyophilic processing on a partial surface by providing a functional group for lyophilic processing on the partial surface of a liquid discharge head for recording by discharging recording liquid constituting at least a part of the inner face having the recording liquid internally filled to be in contact therewith, which comprises the following steps of:
firstly, providing the partial surface with liquid containing subdivided products having a first portion and a second portion obtainable by cleaving polymer for giving functional group having the first portion provided with the functional group, and the second portion having a group of substantially the same or the same interfacial energy as the surface energy of the partial surface but different from the interfacial energy of the functional group;
secondly, orientating the second portion of the subdivided products to the partial surface side on the partial surface, and the first portion to the side different from the partial surface; and
thirdly, condensing at least parts of subdivided products themselves orientated on the partial surface to effectuate the polymerization thereof.
Also, the surface modifying method for performing lyophilic processing on a partial surface by providing a functional group for lyophilic processing on the partial surface of a liquid discharge head for recording by discharging recording liquid constituting at least a part of the inner face having the recording liquid internally filled to be in contact therewith, comprising the following steps of:
firstly, providing the partial surface with liquid having dissolved therein dilute acid, volatile improver for giving affinity to the partial surface, and processing agent having polymer provided with a first portion having a group of substantially the same or the same interfacial energy as the surface energy of the partial surface, and a second portion having a group of different interfacial energy from the interfacial energy;
secondly, removing the infinity improver by giving heat to the partial surface;
thirdly, concentrating the dilute acid to cleave polymer in the processing agent; and
fourthly, condensing the cleaved polymer on the partial surface, while orientating the first portion of the polymer toward the partial surface, and the second portion to the different from the partial surface.
Also, the surface modifying method for performing hydrophilic processing on a partial surface having hydrophobic property to form at least a part of the inner face of a liquid discharge head for recording by discharging recording liquid having the recording liquid internally filled to be in contact therewith, comprising the step of cleaving polymeric compound having a hydrophilic group and a hydrophobic group to generating subdivided products, and orientate the hydrophilic group toward the partial surface side, and the hydrophobic group in the direction different from the hydrophobic group for the adhesion thereof to the partial surface.
Also, the surface modifying method for performing lyophilic processing on a partial surface by providing a functional group for lyophilic processing on the partial surface of a liquid discharge head for recording by discharging recording liquid constituting at least a part of the inner face having the recording liquid internally filled to be in contact therewith, comprising the steps of firstly, providing the partial surface with liquid containing polymer different from the formation material of the partial surface having a first portion with the functional group, and a second portion having a group of substantially the same or the same interfacial energy as the surface energy of the partial surface, but different from the interfacial energy of the functional group; and secondly, orientating the second portion toward the partial surface, and the first portion to the side different from the partial surface.
Further, this method comprises a third step of providing catalyst for use of polymeric cleavage in the liquid containing polymer in the first step; and a forth step of cleaving the polymer on the partial surface utilizing the catalyst for use of polymeric cleavage to make subdivided productd polymer.
Further, this method comprise a step of binding the subdivided productd polymer on the partial surface.
In accordance with the surface modifying method of the present invention, it becomes possible to provide the orifice surface with water-repellent property with ease by allowing the water-repellent film to be exposed by cutting off the hydrophilic film by the laser irradiation or blade cleaning without causing any chemical changes on the water-repellent film even if processing liquid adheres to the orifice plate surface where the water-repellent film is formed so that the hydrophilic film is formed on the water-repellent film when the processing liquid is provided for the inner face for the execution of surface modification.
The liquid discharge head of the present invention is the one for recording by discharging recording liquid provided with a hydrophobic surface on a partial surface forming at least a part of inner face having the recording liquid internally filled to be in contact therewith, the hydrophobic surface being modified to be hydrophilic surface, in which subdivided products having a hydrophilic group and a hydrophobic group are generated by cleaving polymeric compound having the hydrophilic group and the hydrophobic group, and the hydrophobic group is orientated toward the hydrophobic surface side, and the hydrophilic group is orientated in the direction different from the hydrophobic group to adhere to the hydrophobic surface.